ProgrammingError: relation "django_session" does not exist error after installing Psycopg2

I started to develop a Django based web application. Everything was fine until I installed Psycopg2 for my database which I created in PostgreSql. Now when I'm trying to open any page in my site, it throws ProgrammingError: relation "django_session" does not exist error.

Request Method:     GET
Request URL:    http://127.0.0.1:8000/login/
Django Version:     1.7
Exception Type:     ProgrammingError
Exception Value:    

relation "django_session" does not exist
LINE 1: ...ession_data", "django_session"."expire_date" FROM "django_se...
                                                             ^

Exception Location:     /home/alex/.virtualenvs/startDjango/local/lib/python2.7/site-packages/django/db/backends/utils.py in execute, line 65
Python Executable:  /home/alex/.virtualenvs/startDjango/bin/python

This is my database setting in settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'myDB',
        'USER': 'alex',
        'PASSWORD': 'mypassword',
        'HOST': '127.0.0.1',
        'PORT': '5432',
    }
}

I'm developing in virtualenvs

Any idea how to fix this? Thanks

If you change the database, you should create database for the new database.

Use manage.py migrate command. (or manage.py syncdb if you used it for old database).